This SBIR Fast-Track project will create an innovative new system for lower limb prosthetic alignment. Direct real-time measurements of force and moment at the base of the posthetic socket will be input for a newly developed algorithm in the Computerized Prosthetic Alignment System (ComPAS). It will assist prosthetists in the critical task of proper alignment. Previous investigators have clearly indicated a need for such a system, while noting the theoretical feasibility of using instrumentation to help a prosthetist improve prosthetic alignment. Previous efforts have not produced a successful system. Based on preliminary work we believe our new approach can successfully be developed into a clinically relevant, commercially viable system for lower limb prosthetic alignment. ComPAS will be an integrated system that is easy to use and intuitive to the prosthetist. It will be reasonably priced and we will seek a reimbursement code for its use so the system can 'pay for itself.' It will have near universal application in lower limb prostheses without special accommodation by the prosthetist and be used in both static and dynamic situations. The patient will be untethered and the system will be used in a normal office or clinic environment. Automated measurement and interpretation of gait parameters will be translated into user-friendly indicators that indicate to the prosthetist how to improve the alignment of the prosthesis. Phase I work will focus on building prototype hardware and software and demonstrating the efficacy of our approach. Phase II will refine the physical packaging and clinical capabilities, and will undertake more extensive scientific validation of the system. Phase I work will be comprised of the following four Specific Aims: 1. Design and Build Prototype ComPAS, 2. Refine Alignment Detection Algorithm, 3. Prosthetic Alignment Testing Using Proof of Concept ComPAS Prototype, 4. Clinical Review. Phase II work will build from the results and lessons learned from the Phase I project which focused on demonstrating proof of concept of a heuristic method for refining an algorithm to recognize misalignment from force and moment data collected at the base of the prosthetic socket during walking. Phase I feedback from clinical prosthetists and other experts in prosthetic gait will also be used to guide Phase II development. Phase II work will consist of the following 5 Specific Aims: 1. Design and Build Definitive ComPAS Hardware, 2. Design ComPAS Software Interface, 3. Refine Alignment Detection Algorithm, 4. System Testing, 5. Develop Proposed Criteria for Optimal Alignment. CYMA has an exceptional team with over 62 combined years of experience in the field of prosthetic research. We have specific knowledge of the field and the technical and business skills required for successful completion of the proposed development.